A man who accused a retired senior police officer of assaulting him with a baton during Hong Kong’s 2014 Occupy protests on Tuesday denied exaggerating his injuries to take revenge on police over an earlier, separate alleged assault.

But Osman Cheng Chung-hang, 28, admitted he was confused about where the baton had hit him, after giving three versions to police and the court as he testified against Frankly Chu, 57.

Chu, a former superintendent, faces one count of assault occasioning actual bodily harm, alleging that he assaulted Cheng outside Shanghai Commercial Bank on Nathan Road in Mong Kok on November 26, 2014. Chu denied the charge.

Eastern Court heard officers had begun a clearance operation the day before the alleged attack. They were executing a court injunction to stop protesters from occupying the busy shopping district in a civil disobedience movement for greater democracy.

On Tuesday, Cheng admitted going to Mong Kok on November 25, the day before the alleged assault by Chu, during which he claimed he was kicked and injured by an officer he identified as PC9401.

At the time he posted on Instagram: “Brain-dead 9401, I will remember you kicked me.”

But the court heard he did not report the matter to police, or ask a doctor to examine that injury even while he was checking for injuries from the baton strike he got a day later.

That medical examination on November 28 found that he suffered three injuries, including a horizontal, linear injury on the left of his neck.

In court, Cheng testified before Principal Magistrate Bina Chainrai that he sustained injuries on his right shin, right elbow and the right part of his neck outside the bank on November 26.

Defence lawyer Peter Pannu pointed out that that account was different from what Cheng told police. Cheng first reported that Chu caused injuries to “the back side of my head” before making another statement that identified his injury “in the middle between the left side of the neck and the shoulder”.

When asked to explain the discrepancy, Cheng replied that the officer who took the report had got mixed up. “Because you can see from the police video it was really on the right,” he said.

But he was then shown another statement, which recorded that he “suddenly felt a hard object hit the back side of my neck on the left”.

“So a different officer made a mistake?” Pannu asked.

Cheng made a loud sigh, and leaned back and forth on the witness stand. He briefly covered his face with both hands before flipping through his statements in a quick motion.

“Sorry, excuse me, perhaps I did not remember that,” he said. “I was confused because this has lapsed for three years.”

Later he added: “Let’s not talk about left or right. The back of the head and the neck are more or less the same body part.”

Pannu then suggested that the downward movement of the baton had never touched any part of his neck or the back of his head.

“I put it to you that the defendant impacted you between your shoulder blades at the back,” Pannu said. Cheng disagreed.

But the lawyer went on: “Witness, you have exaggerated your injuries, your sufferances and the severity.”

“I disagree,” Cheng replied.

“I put it to you,” Pannu continued, “that your anger against PC9401 for the events on November 25 has meant that you have gone on to exaggerate and take revenge against the police.”